if you are talking about the easiest way up, I would say the spring time before summer exposes all kinds of nasty rock. I have climbed n ride baker in ealry may and it was good. Colfax should be fine that time too, weather permitting.

If you are talking about the ice line on colfax, no idea how long that season lasts. I saw that Roger Strong climbed it this year.

usually open by may. depending on how much snow we get this winter (currently getting plenty) you may have to walk a little bit to get to actual TH. they don't plow it for a opening date. just melt out.